The News-Herald. [volume] (Hillsboro, Highland Co., Ohio) 1886-1973, 1887-03-31

lamp compulsory on the ground that
difficulties might thereby be thrown in
the way of introducing improvements
in future, it is nevertheless desirable
that some control should be exercised in
reference to the kind of lamps to be en-
ployed in coal-mines, and that only those
lamps should be used which are author
lied from time to time by the Secretary
of State.
Fire-damp, however, is not the most
formidable of the causes of colliery
explosions. It is doubtful, indeed,
whether single one of the more dis
astrous explosions of modern times can
be directly and wholly attributed to its
action. 1t is significant chat violent
explosions seldom occur nowadays in
very wet pits, although the air in them
frequently contains fire-damp. More
over, when explosions do occur in such
pits they rarely extend over a large
area, and the loss of life from them is
comparatively small. Such catastro-
phes as those of Abercarne, Risca,
Seaham and Penygraig, where
hundreds of men and boys are
killed. and where evidence of the ex-
plosion is to be met with in nearly all
parts of the pits. almost invariably
happen in dry and dusty pits. 1t hardly
admits of question that explosions of
this kind are dependent upon the pres
ence of this dust. Dust explosions in
flour-mills have long been known, but
it is only within the last few years that
the action of finely divided coal-dust in
initiating or propagating colliery ex-
| plosion has received much attention.
The atmosphere of deep dry mine is
always impregnated with more or less
dust. 1t settles everywhere, not only in
the working places, but in the intake
and haulage roads. 1t is not only on
the floor, but hangs from the roof
and timbers, and is heaped up on the
lodges. A violent movement Of the air
dislodges it in clouds; if a naked flame
be introduced into such cloud it in
flames with explosive violence and the
conclusion of air is followed by fresh
clouds of dust through which the flame
is propagated.
| the smutty grain
| With sudden blaze difIus'd infamos the air."
Milton said this of gunpowder; it is
even truer of coal-dust.
Now there are many conditions in the
ordinary working of coal mine which
may occasion these violent movements
of the air, and chief among them is
the prevalence of what is techni-
cally known as "shot-fring"-that is,
blasting by means of gunpowder. Gum
powder is used in the mine either for
bringing down the coal or for remoring
stone, in order, for example, to make
roads for the passage of horses. and for
engine planes, etc. A hole is driven or
drilled into the coal or stone, into
which certain quantity of powder, to-
gether with fuse, is introduced, and
the rest of the hole is "stemmed" or
"tamped'-that is, filled up with small
stones and earth or, too frequently,
with small coal itself. The fuse is ig-
nited and the workmen retire either in
to a "refuge hole' or round corner
until the blast is made, Occasionally
it happens when the charge of gum
powder is too large, or when it is i'm
perfectly stemmed. or when the rock is
unusually hard, that the powder blows
out the stemming and there is violent
conclusion of air. and from the mouth
of the drill-hole there issues flame
the length of which will be greatly
increased if small coal has been
used in the stemming. Indeed. it is
not necessary for the shot to be 'blown
OUT to produce either the flame or
conclusion of air sufficient to dislodge
the inflammable dust. We have here a
condition of things which may be high
ly dangerous in dusty pits. 1t has been
proved over and over again that shot
firing has been the immediate precursor
of some of the most disastrous colliery
explosions on record. The influence of
dust in at least propagating an explosion
is now generally recognized by mining
engineers and colliery managers, but
it is still moot point with some
whether it is capable of initiating an
explosion or, indeed, Of propagating it
in the absence of fre-damp. There is,
however, a considerable body of evil
dence to show that whilst the explosive
character of dusty atmosphere may
be greatly augmented by the presence
of tire-damp, dust alone may be suffi-
cient to bring about the most disastrous
| explosions. 1t is known that explosions
have occurred simultaneously with the
firing of shots in stone, and certain of
these shots have been fired in a dusty
main intake-road, and at points where
currents of air of over 10000 cubic feet
per minute were passing. 1t is almost
uncomfortable. except on the theory of
the sudden outburst of gas at places
where tits in the highest degree improb-
able that such outbursts could occur,
that such air could contain any sensible
quantity of fire-damp. The concussion
OF air would certainly dislodge large
clouds of dust from the roof and from
the floor, and this once ignited, would
cause an explosive wave which would
travel throughout the pit or so long as
the ignition was maintained by fresh
clouds of dust.
OF late years the use of explosives in
coal mines has been considerably re-
stricted, and some people have gone so
far as to demand their absolute prohi-
L